Fluorescent products derived from the reaction of primary amines and components in peroxidized lipids

Classical pathology demonstrated that fluorescent lipofuscin granules developed in the aging cells. Age-related fluorescent substances increase with lipid oxidation of tissues. The fluorophores of these substances have been considered to be conjugated Schiff bases between primary amines or proteins and malonaldehyde. Our recent studies showed that the fluorophores produced in the in vitro reaction of primary amines or proteins with malonaldehyde are 1,4-dihydropyridine-3,5-dicarbaldehydes, whose fluorescence characteristics are similar to but not always the same as those of the age-related fluorescent substances. The in vitro reaction of primary amines or proteins with oxidized lipids produces fluorescent substances similar to those in the aging cells or tissues. Monofunctional aldehydes can also participate in the formation of the fluorescent substances. The fluorescent substances produced from the reaction of primary amines or proteins with monofunctional aldehydes showed spectra close to those of the age-related fluorescent substances.